1. Field
One or more embodiments described herein relate to an image sensor.
2. Description of the Related Art
An image sensor is a device that transforms incident light to an electric signal. Examples include a charge coupled device (CCD) image sensor and a complementary metal oxide semiconductor (CMOS) image sensor. To improve sensing performance, a backside illuminated image sensor (BIS) has been developed that performs photoelectric transformation in response to incident light passing through a back surface of a semiconductor substrate.